text: /**
   * @file BProcess.h
   * @author Ambroz Bizjak <ambrop7@gmail.com>
   * 
   * @section LICENSE
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the author nor the
   *    names of its contributors may be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
   * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #ifndef BADVPN_BPROCESS_H
  #define BADVPN_BPROCESS_H
  
  #include <stdint.h>
  #include <unistd.h>
  
  #include <misc/debug.h>
  #include <misc/debugerror.h>
  #include <structure/LinkedList1.h>
  #include <base/DebugObject.h>
  #include <system/BUnixSignal.h>
  #include <base/BPending.h>
  
  /**
   * Manages child processes.
   * There may be at most one process manager at any given time. This restriction is not
   * enforced, however.
   */
  typedef struct {
      BReactor *reactor;
      BUnixSignal signal;
      LinkedList1 processes;
      BPending wait_job;
      DebugObject d_obj;
  } BProcessManager;
  
  /**
   * Handler called when the process terminates.
   * The process object must be freed from the job context of this handler.
   * {@link BProcess_Terminate} or {@link BProcess_Kill} must not be called
   * after this handler is called.
   * 
   * @param user as in {@link BProcess_InitWithFds} or {@link BProcess_Init}
   * @param normally whether the child process terminated normally (0 or 1)
   * @param normally_exit_status if the child process terminated normally, its exit
   *                             status; otherwise undefined
   */
  typedef void (*BProcess_handler) (void *user, int normally, uint8_t normally_exit_status);
  
  /**
   * Represents a child process.
   */
  typedef struct {
      BProcessManager *m;
      BProcess_handler handler;
      void *user;
      pid_t pid;
      LinkedList1Node list_node; // node in BProcessManager.processes
      DebugObject d_obj;
      DebugError d_err;
  } BProcess;
  
  /**
   * Initializes the process manager.
   * There may be at most one process manager at any given time. This restriction is not
   * enforced, however.
   * 
   * @param o the object
   * @param reactor reactor we live in
   * @return 1 on success, 0 on failure
   */
  int BProcessManager_Init (BProcessManager *o, BReactor *reactor) WARN_UNUSED;
  
  /**
   * Frees the process manager.
   * There must be no {@link BProcess} objects using this process manager.
   * 
   * @param o the object
   */
  void BProcessManager_Free (BProcessManager *o);
  
  struct BProcess_params {
      const char *username;
      const int *fds;
      const int *fds_map;
      int do_setsid;
  };
  
  /**
   * Initializes the process.
   * 'file', 'argv', 'username', 'fds' and 'fds_map' arguments are only used during this
   * function call.
   * If no file descriptor is mapped to a standard stream (file descriptors 0, 1, 2),
   * then /dev/null will be opened in the child for that standard stream.
   * 
   * @param o the object
   * @param m process manager
   * @param handler handler called when the process terminates
   * @param user argument to handler
   * @param file path to executable file
   * @param argv arguments array, including the zeroth argument, terminated with a NULL pointer
   * @param params.username user account to run the program as, or NULL to not switch user
   * @param params.fds array of file descriptors in the parent to map to file descriptors in the child,
   *            terminated with -1
   * @param params.fds_map array of file descriptors in the child that file descriptors in 'fds' will
   *                be mapped to, in the same order. Must contain the same number of file descriptors
   *                as the 'fds' argument, and does not have to be terminated with -1.
   * @param params.do_setsid if set to non-zero, will make the child call setsid() before exec'ing.
   *                         Failure of setsid() will be ignored.
   * @return 1 on success, 0 on failure
   */
  int BProcess_Init2 (BProcess *o, BProcessManager *m, BProcess_handler handler, void *user, const char *file, char *const argv[], struct BProcess_params params) WARN_UNUSED;
  
  /**
   * Initializes the process.
   * 'file', 'argv', 'username', 'fds' and 'fds_map' arguments are only used during this
   * function call.
   * If no file descriptor is mapped to a standard stream (file descriptors 0, 1, 2),
   * then /dev/null will be opened in the child for that standard stream.
   * 
   * @param o the object
   * @param m process manager
   * @param handler handler called when the process terminates
   * @param user argument to handler
   * @param file path to executable file
   * @param argv arguments array, including the zeroth argument, terminated with a NULL pointer
   * @param username user account to run the program as, or NULL to not switch user
   * @param fds array of file descriptors in the parent to map to file descriptors in the child,
   *            terminated with -1
   * @param fds_map array of file descriptors in the child that file descriptors in 'fds' will
   *                be mapped to, in the same order. Must contain the same number of file descriptors
   *                as the 'fds' argument, and does not have to be terminated with -1.
   * @return 1 on success, 0 on failure
   */
  int BProcess_InitWithFds (BProcess *o, BProcessManager *m, BProcess_handler handler, void *user, const char *file, char *const argv[], const char *username, const int *fds, const int *fds_map) WARN_UNUSED;
  
  /**
   * Initializes the process.
   * Like {@link BProcess_InitWithFds}, but without file descriptor mapping.
   * 'file', 'argv' and 'username' arguments are only used during this function call.
   * 
   * @param o the object
   * @param m process manager
   * @param handler handler called when the process terminates
   * @param user argument to handler
   * @param file path to executable file
   * @param argv arguments array, including the zeroth argument, terminated with a NULL pointer
   * @param username user account to run the program as, or NULL to not switch user
   * @return 1 on success, 0 on failure
   */
  int BProcess_Init (BProcess *o, BProcessManager *m, BProcess_handler handler, void *user, const char *file, char *const argv[], const char *username) WARN_UNUSED;
  
  /**
   * Frees the process.
   * This does not do anything with the actual child process; it only prevents the user to wait
   * for its termination. If the process terminates while a process manager is running, it will still
   * be waited for (and will not become a zombie).
   * 
   * @param o the object
   */
  void BProcess_Free (BProcess *o);
  
  /**
   * Sends the process the SIGTERM signal.
   * Success of this action does NOT mean that the child has terminated.
   * 
   * @param o the object
   * @return 1 on success, 0 on failure
   */
  int BProcess_Terminate (BProcess *o);
  
  /**
   * Sends the process the SIGKILL signal.
   * Success of this action does NOT mean that the child has terminated.
   * 
   * @param o the object
   * @return 1 on success, 0 on failure
   */
  int BProcess_Kill (BProcess *o);
  
  #endif
  